The sum of two numbers is 28 and their product is seven. Find the sum of the reciprocals of the numbers.

This one has me confused. How can their product equal 7 if 7 is prime?

1+27 027 14+14 196

2+26 052 13+15 195

3+25 075

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- Feb 28th 2007, 04:50 PMceasar_19134The sum on two numbers in 28...
The sum of two numbers is 28 and their product is seven. Find the sum of the reciprocals of the numbers.

This one has me confused. How can their product equal 7 if 7 is prime?

1+27 027 14+14 196

2+26 052 13+15 195

3+25 075 - Feb 28th 2007, 05:05 PMPlato
This is just a very basic algebra problem.

x+y=28

xy=7

(1/x)+(1/y)=? - Feb 28th 2007, 05:36 PMSoroban
Hello, ceasar!

Quote:

The sum of two numbers is 28 and their product is seven.

Find the sum of the reciprocals of the numbers.

This one has me confused.

How can their product equal 7 if 7 is prime?

WHO said these are whole numbers ??

We have: .x + y .= .28 . [1]

. . . . . . . . .xy . = . .7 . .[2]

Divide [1] by [2]: . x + y . . .28

. . . . . . . . . . . . . ------- .= .---

. . . . . . . . . . . . . . .xy . . . . 7

. . . . . . . . . . . x . . .y

And we have: .--- + --- .= .4

. . . . . . . . . . .xy . . xy

- - - . . . . . .1 . . 1

Therefore: - -- + -- .= .4 . . . . ta-*DAA!*

- - - . . . . . .y . . x